It stands to reason that would want stretch a muscle if it is tight, right?

I wish that it were that simple, but as with most things it is not.  We have all heard the benefits of flexibility from early on in school when we were told that we should be able to touch our toes. Flexibility is important, but it depends on what is causing muscles to be inflexible as to whether or not you should be stretching them.

Muscles can become tight for a number of reasons.  One reason that muscles become tight is because they are held in their shortened position for an extended period of time.  Muscles that are tight from being in a shortened position respond well to stretching and should be stretched regularly.  Shortened and tight muscles in the hip are common in desk workers due to the amount of time spent seated.  Muscles can also be tight from overuse, for example if you push yourself during exercise more than you typically do and then experience tightness.  This type of muscle tightness will also typically respond well to stretching.  Some muscles become tight in order to protect the body, which we will talk about next.

So when should you not stretch a muscle?

There are a few muscles that commonly “tighten up” to protect the body, but I am going to focus on the one that I see the most and the one that causes the most problems, the hamstrings.  Due to what we have heard about flexibility over the years it is easy for us to assume that tight hamstrings are a sign of being out of shape, but we need to understand another  reason why hamstrings become tight.  Hamstrings often become tight or restrictive to protect the lower back, sounds strange I know.  Lets take a look at the anatomy and see how this might happen.

Spinal cord under pressure of bulging disc

This is a picture of a few vertebrae in the lumbar spine, the left of the picture is the back and the right of the picture is the front of the spine.  The bony fingers that you see on the left side of the picture are the bumps that you feel when you run your fingers up and down your spine. The grey cushions that are sandwiched between each vertebrae are called intervertebral discs.  Each disc has a nucleus that has a jelly-like material that can push outward and cause a herniated disc which is what you see in the middle of the picture in red. There are a number of things that will caused increased damage to a herniated disc, but the most detrimental is flexing the spine or bending forward.  When you bend forward the material in the disc is pushed farther back toward the nerve, which I call the “jelly doughnut effect.”


jelly doughnut When you squeeze one end of a jelly doughnut the jelly migrates to the opposite end of the doughnut.  This is exactly what happens in the spine when we bend forward and the pressure is put on the front of the spine migrating the disc material to the back of the spine where the sensitive lumbar nerves are located causing back pain.  This is another reason why you should never do crunches or situps.



What causes our hamstrings to become tight?

Our nervous system knows that bending forward will continue to damage the already injured disc so the brain tells the hamstrings to tighten in order to prevent forward bending, keeping you from touching your toes. Unfortunately we read this sign incorrectly and see this as a need to stretch our hamstrings which continues to injure the disc and perpetuate the tightness in the hamstrings causing a viscous cycle.

What do I do if I have tight hamstrings?

If your hamstrings are tight because you have been sitting to long then stretching them might help, but you want to make sure that when you stretch them by bending from the hip and not the lower back.  Think of having a rod that goes through your hips and rotating around that rod while keeping the lower back straight.

If you hamstring tightness is due to nerve irritation or a disc herniation then you should seek care to determine what the best approach should be for you to manage your case.  We treat these types of complaints in our office and would be happy to help you with any questions you might have.  You can reach us on our Contact Us page.